diff --git a/src/protocol/eval.rs b/src/protocol/eval.rs
index 98ac5816ce85366414d4bd5075963fe5bd1b81eb..4e77eec893d793d355ee1b192726e82ebbbe8577 100644
--- a/src/protocol/eval.rs
+++ b/src/protocol/eval.rs
@@ -1533,6 +1533,7 @@ impl Store {
                     BinaryOperator::GreaterThan => Ok(left.gt(&right)),
                     BinaryOperator::GreaterThanEqual => Ok(left.gte(&right)),
                     BinaryOperator::Remainder => Ok(left.modulus(&right)),
+                    BinaryOperator::Add => Ok(left.plus(&right)),
                     _ => unimplemented!("{:?}", expr.operation),
                 }
             }